Collagen, which is a glycoprotein rich in proline and hydroxyproline, is especially used as such or combined with other polypeptide bases in the treatment of wrinkles and other unaesthetic blemishes linked to poor skin hydration and elasticity. The animal origin of collage, however, limits its use because of the risks of contamination from viruses and toxins. Though the compounds of vegetable origin do not involve these risks, so far their use in cosmetics has been quite limited: for examples, cosmetic formulations are known which contain raw extracts of such plants as Aloe or even entire minced vegetables such as avocado.
Vegetable glycoproteins, called extensines, that are produced from vegetable cells in the proliferation stage and have a similar structure to animal collagen, are known. EP-A-0 533 4078 discloses the cosmetic use of extensines having an average molecular weight above 100,000 Daltons. However, the methods for the extraction of extensines described to date, which involve the extraction of vegetable materials of various origin by means of aqueous saline solutions, followed by purification with strong acids such as trichloroacetic acid, do not allow to obtain suitable products for cosmetics, due to problems concerning solubility, stability, repeatability and consistency of their chemical-physical characteristics.